Hey guys. I opened up my pc today to switch my fan controller around and when I tried to power it on afterwards it lights up, shuts down after a second, and then powers back on, however my monitor gets no signal from it. all the lights inside seem to be on, fans are spinning, and I rechecked the connections to make sure nothing was loose.

I had my power button set to put the computer to sleep when pressed while on... now it does the default thing of turning it off. not sure how relevant this is.

If anyone has any ideas as to what the problem may be or even some help as to how to go about diagnosing these things it would be really appreciated... I really don't want to have to pay someone to take a look and though I built it I wouldn't know where to start in terms of diagnosis. thanks a lot.

I had a similar issue a few years back. I was transporting my PC and when I made it back home my PC would not boot up. Everything seemed normal inside, but I unplugged every cable and plugged them back in. The POS still did not boot up properly. Eventually I started unplugging components and putting them back in properly, and the PC started to work again. It was the video card that had been shaken loose, even though it appeared to be in its correct position in the case.

TLDR: Remove the video card and plug it back in. If that does not work, just go down the list of components because they might be loose. If it isn't a loose connection somewhere, you should take it in to a pro.

Sounds like something's not plugged in. Had a similar issue over the weekend where I was replacing a power supply. No display, but I would be able to turn it on, off, etc. Ended up forgetting to plug into a 12V port near the CPU and motherboard outputs. That fixed my issue.

Pull and reseat the ram too.

thanks guys, I'll give it a try.